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HI-POT LOADING is an exciting method of quad miniaturization utilizing inductance and capacitance at the high potential points of a four sided quad element.
An outstanding feature and advantage of this method of quad size reduction over pervious methods is that current distribution in both upper and lower elements is in phase on all bands, and current maximum is always at center regardless of the degree miniaturization employed. This differs from other methods miniaturization in which optimum current phasing on more than one band is difficult to attain and mult-band operation is generally a compromised design.
With HI-POT loading, only a single quad element or loop is required for multi-band operation.
As quad size is reduced, the average current in the loop is increased, and since signal output is a direct function of radiator current, HI-POt loading affords maximum watts output per inch of antenna.
PRINCIPLE OF END LOADING
This system allows a major reduction in antenna element length and differs from other multiband antennas in that the highest frequency of the desired operation rather than by the lowest frequency as with conventional designs.
To explain the operation of the antenna, we will treat the end loading sections as ordinary series tuned circuits with lumped inductance and capacitance . As tuned circuits they exhibit zero reactance at resonance. At frequencies above resonance they appear as an inductive reactance. The end loading employed differs from conventional end loading in that the loading sections mounted at the end of the radiators are designed so that their resonant frequency is always lower than the radiator frequency. Having a lower resonant frequency they, therefore, appear as an inductive reactance with high impedance and are thus in effect isolated from the radiator and inactive when the antenna is operated at its highest frequency which would be the radiators natural resonant frequency increased slightly due to the loss of end effect.
Referring to FIGURE ONE, a quarter wave dual frequency antenna, the end loading section, consisting of L and C as shown in the right half view is , designed so that its resonant frequency is lower than the radiator frequency, which we will refer to as F , but slightly higher than the frequency at which it is to operate, F Having a higher resonant frequency the loading section therefore appears as a capacitive reactance at the lower frequency F and provides capacitive loading to the radiator to make the combination (radiator and loading section) resonant at the desired lower operating frequency F When operated at the higher radiator frequency F the top loading section appears as an inductive reactance and in effect isolates itself as described earlier. Under these conditions, the antenna is then resonant at two separate frequencies. Changing the resonant frequency of either section by 10 to12% has negligible effect on the other section ( a very important feature in multiband operation).
Additional loading sections may be added in series or parallel to provide for operation on other frequencies.
The foremost advantage realized by the use of the multiple hat end loading principle is the high efficiency of the resultant miniature multiband antenna system. For example, it is now possible to operate on six of our most popular amateur frequencies such as 10,12,15, 17, 20 or 40 meters with practically the same overall efficiency of antennas 3 times larger than he Hybrid Quad antenna. Again, the basic miniaturization principle of removing the least useful portion, the ends, and retaining the center is universally recognized by antenna engineers as the most affective method of reducing antenna size while maintaining maximum efficiency. Installation and maintenance costs are greatly reduced due to the smaller size and lighter weight of the Hybrid Quad Antennas.
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